This invention relates to data security systems, and more particularly, to data security systems interfacing with computers.
The encryption of digital data has been widely recognized as a need in the computer industry in order to protect data which is transmitted over unsecure data transmission paths. A standard data encryption algorithm has been proposed by the National Bureau of Standards as described in the Federal Information Processing Standard Publication 46 and available through the National Technical Information Service.
Various systems have been used in the past to implement this or similar algorithms. The principle methods being either software implementation of the algorithm which utilizes the central processor of the computer, or a serial encryption device which encrypts or decrypts data either just before it enters the computer or just after it exits from the computer. However these systems have several undesirable effects in that they reduce the data transfer time in the case of the serial devices and tie up the central processor in the case of the software implementation. Moreover the software implementation is relatively time consuming.
Therefore it can be appreciated that a data encryption system which does not interfere with the direct flow of data and does not tie up the central processor for an extended period of time is highly desirable.